Photoacoustic Signal Enhancement: Towards Utilization of Low Energy Laser Diodes in Real-Time Photoacoustic Imaging

Abstract

In practice, photoacoustic (PA) waves generated with cost-effective and low-energy laser diodes, are weak and almost buried in noise. Reconstruction of an artifact-free PA image from noisy measurements requires an effective denoising technique. Averaging is widely used to increase the signal-to-noise ratio (SNR) of PA signals; however, it is time consuming and in the case of very low SNR signals, hundreds to thousands of data acquisition epochs are needed. In this study, we explored the feasibility of using an adaptive and time-efficient filtering method to improve the SNR of PA signals. Our results show that the proposed method increases the SNR of PA signals more efficiently and with much fewer acquisitions, compared to common averaging techniques. Consequently, PA imaging is conducted considerably faster.

Overview of Ultrasound Detection Technologies for Photoacoustic Imaging

“…Another modality that directly benefits from ultrasound transducer technology is photoacoustic imaging (PAI). PAI is an emerging modality that uses a combination of optical excitation and acoustic detection for visualizing vascular, functional, and molecular changes within living tissue [2][3][4][5][6][7][8][9][10][11]. As opposed to the optical imaging modalities such as optical coherence tomography [12] that employs ballistic photons, PAI uses diffused photons providing significantly deeper penetration.…”

Photoacoustic image improvement based on a combination of sparse coding and filtering

“…The combination of these different types of noise in the PA signal leads to a low signal-to-noise ratio (SNR) and results in a poor quality reconstructed PA image. [27][28][29][30] Several previously reported studies have attempted to improve the image reconstruction algorithms to achieve noise-and artifact-free PA images. However, acquiring high-quality PA images from noisy signals requires an effective denoising technique, [31][32][33][34][35][36] prior to utilizing reconstruction algorithms.…”

“…29 Alternatively, the adaptive filtering method without any prior knowledge requirement was proposed for low-energy pulse laser diodes PA signal enhancement. 28 They average fewer frames, in comparison with conventional averaging techniques, which leads to shorter acquisition time. 28 Notwithstanding, the requirement of frames averaging in the latter method compromises the imaging speed.…”

“…28 They average fewer frames, in comparison with conventional averaging techniques, which leads to shorter acquisition time. 28 Notwithstanding, the requirement of frames averaging in the latter method compromises the imaging speed.…”

Development of Low-Cost Fast Photoacoustic Computed Tomography: System Characterization and Phantom Study

“…Photoacoustic imaging (PAI) is a promising imaging technique that combines higher imaging contrast of optical imaging with deeper penetration of ultrasonic imaging [1][2][3]. A nanosecond pulsed laser deposits energy onto a light absorbing sample, causing a local temperature increase and subsequent thermal expansion through the thermoacoustic effect [2,[4][5][6][7][8]. This expansion causes a localized pressure increase, which propagates from the sample to be imaged, by an ultrasound transducer, similar to a traditional ultrasound detection system.…”